1. Field of the Invention
The present invention relates to a center hub cap for a vehicle wheel adapted to be secured to a hub of a vehicle.
2. Description of the Related Art
A center hub cap is generally composed of a synthetic resin material, and used in combination with a vehicle wheel which includes a center portion recessed from an axially outer surface side of the wheel and defined by an inner peripheral wall. The center portion of the wheel has a bottom wall with an axially inner surface to be brought into abutting engagement with an axially outer surface of the hub. The bottom wall of the center portion of the wheel is to be secured to the hub by a plurality of fastener elements, such as bolts extending through the bottom wall.
The center hub cap is to be engaged with the inner peripheral portion of the center portion of the wheel, and includes a substantially dish-like main body composed of a synthetic resin material, having axially inner and outer surfaces, as well as retainers for retaining the hub cap in engagement with the wheel. As disclosed, e.g. in Japanese Utility Model Application Laid-open Publication No. 63-4,801, the retainers of known center cap include a plurality of retainer legs which are formed integrally with the main body to protrude from the inner surface of the main body, and an annular spring ring composed of a resilient material for urging the retainer legs radially outwardly of the main body toward the inner peripheral wall of the center portion of the wheel. A plurality of support ribs on the inner surface of the main body are arranged adjacent to respective retainer legs, and each formed with a cutout portion to retain the spring ring in place.
In the known arrangement of the center hub cap mentioned above, the combination of the retainer legs and the support ribs which cooperate with each other to retain the spring ring radially of the main body has proved to be quite problematic in that it cannot stably maintain the spring ring in engagement with the retainer legs and to effectively prevent undesired disengagement of the spring ring from the retainer legs axially inwardly of the main body. Needless to say, the spring ring which has been disengaged from the retainer legs does not achieve the desired function of resiliently urging the retainer legs toward the inner peripheral surface of the center portion of the wheel, as a result of which it becomes impossible to stably retain the hub cap in place. While the support ribs could be modified so as to prevent the undesired disengagement of the spring ring axially inwardly of the main body, it then becomes impossible or at least very difficult to mount the spring ring into engagement with the retainer legs.